KR20180097414A - Filter design apparatus of high voltage direct current system and filter design method of therrof - Google Patents

Abstract

According to an embodiment of the present invention, an AC filter design apparatus for an HVDC system comprises: an input unit for receiving data to estimate the filter capacity and the number of filters of an AC filter; and a control unit for calculating a reactive power variation limit amount of a power system connected to the HVDC system, setting a voltage maintaining maximum value and a voltage maintaining target value of the HVDC system, and estimating the filter capacity and the number of filters based on the reactive power variation limit amount, the voltage maintaining maximum value, and the voltage maintaining target value.

Description

TECHNICAL FIELD [0001] The present invention relates to a filter design apparatus and a filter design method for a high-voltage DC transmission system,

The present invention relates to a filter designing apparatus and a filter designing method for a high voltage DC transmission system, and more particularly, to a filter designing apparatus for a high voltage DC transmission system capable of systematically performing capacity determination and number selection of an AC filter used in an HVDC system And a filter design method.

The AC filter for the high voltage direct current (HVDC) system eliminates the harmonics generated during the conversion process of the converter and supplies the reactive power consumed. In HVDC systems, converters absorb reactive power from the AC power system, so there is a need to supply reactive power using an AC filter.

In this case, the reactive power required for the conversion in the converter of the HVDC system is designed so that it can be supplied within the allowable range of the AC power system under normal conditions. Also, in the transient state, the AC filter is designed so as not to exceed the voltage fluctuation limit when the filter is turned on.

In the conventional HVDC system, the capacity of the AC filter is estimated by simply considering the rated voltage of the AC system. Also, the selection of the number of filters has been performed irrespective of the capacity calculation. Furthermore, there was no systematic procedure for calculating the capacity of the AC filter, and the capacity calculation and the number of filters were selected according to the characteristics of each HVDC system in an empirical manner.

Therefore, there is a problem that the AC filter design for the HVDC system is based on inefficient and unstructured analysis, which increases the time required for the design.

An object of the present invention is to propose a filter design algorithm that can systematize the capacity estimation of an AC filter and simultaneously calculate a minimum number of filters when designing an AC filter for an HVDC system.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

The apparatus for designing an AC filter for an HVDC HVDC system according to an embodiment of the present invention includes an input unit for receiving data for calculating a filter capacity and a number of filters of the AC filter; Calculating a reactive power fluctuation threshold of the power system to which the HVDC system is connected, setting a voltage holding maximum value and a voltage holding target value of the HVDC system, setting the reactive power fluctuation threshold value, the voltage holding maximum value, And a controller for calculating the filter capacity and the number of filters based on the value of the filter capacity.

According to another aspect of the present invention, there is provided a method of designing an AC filter for an HVDC system, the method comprising: receiving data for estimating a filter capacity and a number of filters of the AC filter; Calculating a reactive power fluctuation threshold of the power system to which the HVDC system is connected; Setting a voltage holding maximum value and a voltage holding target value of the HVDC system; And calculating the filter capacity and the number of filters based on the reactive power fluctuation threshold, the voltage holding maximum value and the voltage holding target value.

According to the embodiments of the present invention, an AC filter optimized for the HVDC system can be systematically designed by a filter design algorithm that can systematize the capacity estimation of the AC filter and simultaneously calculate the minimum number of filters.

In addition, according to the embodiments of the present invention, it is possible to contribute to the improvement of the stability of the AC power system at the time of filter design by suggesting a step size and number estimation method of the filter required for designing the AC filter.

Further, at the same time, it is possible to contribute to economical efficiency by selecting the minimum number of filters capable of supplying reactive power within a range allowed by the AC power system in a steady state.

1 is a block diagram showing a configuration of an AC filter designing apparatus according to an embodiment of the present invention.
2 is a block diagram showing a detailed configuration of a control unit included in an AC filter designing apparatus according to an embodiment of the present invention.
3 is a view illustrating a design process of an AC filter for an HVDC system according to an embodiment of the present invention.
FIG. 4 is a graph showing a reactive power limit value for each voltage according to a transmission amount of an HVDC system calculated in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.
FIG. 5 is a graph illustrating a reactive power requirement of an HVDC system calculated in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.
FIG. 6 is a graph illustrating a reactive power fluctuation threshold of an AC power system calculated in an AC filter designing process according to an exemplary embodiment of the present invention.
FIG. 7 is a graph illustrating a method of calculating the number of filters in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the technical spirit of the present invention is not limited by the embodiments described below, and other degenerative inventions such as addition, change and deletion of another constituent element and other embodiments included in the technical idea of the present invention Examples can be easily suggested.

The terms used in the present invention are selected as general terms that are widely used in connection with the present technology as much as possible. However, in some cases, there are some terms selected arbitrarily by the applicant. Therefore, it should be understood in advance that the present invention should be grasped as a meaning of a term that is not a name of a simple term. In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed.

1 is a block diagram showing a configuration of an AC filter designing apparatus according to an embodiment of the present invention.

The AC filter design apparatus 100 according to an embodiment of the present invention may be an apparatus for designing an AC filter used in an HVDC system. In this case, the AC filter may be a multiple tuned filter (MTF) or a single tuned filter (STF). However, the present invention is not limited thereto, and the AC filter may include all kinds of filters that can be used in the HVDC system to remove harmonics.

The AC filter design apparatus 100 according to an embodiment of the present invention may include an input unit 110, a storage unit 120, and a controller 130.

The input unit 110 may receive data for designing an AC filter.

Here, the data for designing the AC filter may be data necessary for calculating the filter capacity and the number of filters of the AC filter. For example, data on the transmission amount, voltage, rated capacity, etc. of the HVDC system may be included.

The input unit 110 may receive control data for controlling the operation of the AC filter design apparatus 100.

The input unit 110 may serve as an interface with all the external devices connected to the AC filter design apparatus 100. For this, the input unit 110 may be implemented as a key pad, a dome switch, a touch pad, a jog wheel, a jog switch, or the like.

The storage unit 120 may store data for operation of the AC filter design apparatus 100. Specifically, the storage unit 120 stores the data input to and output from the AC filter design apparatus 100 (for example, data on the amount of transmission of the HVDC system, data on the voltage of the HVDC system, data on the rated capacity of the HVDC system, ), Result data calculated or calculated by the control unit 130, and the like.

For this purpose, a program for processing and control by the control unit 130 may be stored in the storage unit 120. [

The controller 130 may design an AC filter used in the HVDC system.

Specifically, the controller 130 can calculate the reactive power limit value for each voltage according to the transmission amount of the HVDC system and the reactive power required amount for the HVDC system. In this case, the controller 130 can calculate the reactive power fluctuation threshold of the AC power system by summing the reactive power limit value for each voltage according to the transmission amount of the HVDC system and the reactive power required amount for the HVDC system.

The control unit 130 can calculate the difference between the grid reactive power fluctuation threshold corresponding to the voltage holding maximum value and the grid reactive power fluctuation threshold corresponding to the voltage holding target value as the filter capacitance.

The controller 130 can select the maximum value within the error range within which the voltage can be maintained at the interval between the voltage holding target value and the voltage holding maximum value as the number of filters.

A detailed process of calculating the filter capacity and the number of filters by the control unit 130 will be described later in detail with reference to FIG.

Also, the control unit 130 can control the operation of the AC filter designing apparatus 100 as a whole.

The controller 130 may be implemented as a microcontroller or a microprocessor.

2 is a block diagram showing a detailed configuration of a control unit included in an AC filter designing apparatus according to an embodiment of the present invention.

The controller 130 included in the AC filter design apparatus 100 may include a plurality of blocks to estimate the capacity and the number of AC filters. Specifically, the plurality of blocks may include a reactive power threshold calculation block 210, a reactive power requirement calculation block 220, a reactive power variation threshold calculation block 230, a filter capacity estimation and number selection block 240 .

The reactive power threshold value calculation block 210 may calculate the reactive power threshold value.

In this case, the reactive power threshold value calculation block 210 can calculate the reactive power threshold value using the power system simulator. According to one embodiment, a PSS / E (Power System Simulator for Engineering) program may be used as a power system simulator.

Specifically, the reactive power limit value calculation block 210 can set the parameters in the HVDC system model based on the database of the power supply basic plan using the PSS / E program, and set the operating arc angle of the HVDC system in the steady state . Thereafter, the reactive power limit value calculation block 210 may block the HVDC system in the PSS / E program and set the voltage to 0.95 pu, 1.00 pu, 1.02 pu, and 1.05 pu, respectively, by adding the generators bus. In this case, the reactive power threshold value calculation block 210 may perform tidal current calculation according to the transmission amount of the HVDC system and calculate the reactive power threshold value according to the HVDC system transmission amount.

On the other hand, the voltage to be set can be variously set according to the embodiment. Generally, the allowable range voltage of the domestic AC power system is between 0.95 pu and 1.05 pu. Therefore, the reactive power threshold value calculation block 210 divides the allowable range voltage into appropriate intervals and sets the voltage corresponding to the interval.

According to one embodiment, the reactive power threshold value calculation block 210 may calculate the reactive power threshold value so that reactive power can be supplied within an allowable range of the AC power system.

The reactive power requirement calculation block 220 may calculate the reactive power requirement of the HVDC system in response to the converter design technique for the HVDC system.

The reactive power requirement of the HVDC system may be the amount of reactive power required in the corresponding HVDC system. The AC filter supplies the reactive power consumed in the conversion process of the converter. Therefore, the amount of reactive power required in the HVDC system may vary corresponding to the converter used in the HVDC system. Specifically, it may vary depending on the type of converter used in the HVDC system, the capacity or design of the converter, the AC power system associated with the HVDC system, and the like.

The reactive power fluctuation threshold calculating block 230 can calculate the reactive power fluctuation threshold. Here, the reactive power fluctuation threshold may be a threshold value (limit value) at which the reactive power of the AC power system may fluctuate. The reactive power fluctuation threshold calculating block 230 may calculate the reactive power fluctuation threshold by summing the reactive power threshold for each voltage according to the transmission amount of the HVDC system and the reactive power required for the HVDC system.

The filter capacity estimation and number selection block 240 can estimate the capacity of the AC filter used in the HVDC system and select the number of filters based on the filter capacity.

Specifically, the filter capacity calculation and number selection block 240 can calculate the difference between the grid reactive power fluctuation threshold corresponding to the voltage holding maximum value and the grid reactive power fluctuation threshold corresponding to the voltage holding target value as the filter capacity .

In addition, the maximum value within an error range in which the voltage can be maintained at the interval between the voltage holding target value and the voltage holding maximum value can be selected as the number of filters.

Assuming that the reactive power amount to be compensated by the AC filter is the same, the smaller the fluctuation range of the voltage, the smaller the unit capacity of the filter should be designed. In this case, a correspondingly large number of filters are required.

According to one embodiment, the voltage variation rate can be maintained at 2.5%, which is the ratio of the voltage holding maximum value 1.05pu to the voltage holding target value 1.02pu. In this case, the filter capacity can be set as a difference between the system reactive power fluctuation threshold corresponding to 1.05pu and the system reactive power fluctuation threshold corresponding to 1.02pu.

In addition, the number of filters can be selected as the maximum value within an error range capable of maintaining voltage at 1.02pu and 1.05pu intervals. As a result, the number of filters to be designed can be minimized and economic efficiency can be secured.

3 is a view illustrating a design process of an AC filter for an HVDC system according to an embodiment of the present invention.

When designing an AC filter for an HVDC system, the capacity and number of AC filters to be used in the HVDC system can be estimated. The algorithm for designing the AC filter for the HVDC system is as follows.

The AC filter design apparatus 100 calculates the reactive power limit value for each voltage according to the transmission amount of the HVDC system (S301).

According to one embodiment, the controller 130 of the AC filter design apparatus 100 can calculate the reactive power limit value so that reactive power can be supplied within a range allowed by the AC power system.

The control unit 130 of the AC filter design apparatus 100 can calculate the reactive power limit value using the power system simulator. Specifically, the control unit 130 may set parameters in the HVDC system model using the power system simulator and set the operating angle of the HVDC system in the steady state. Thereafter, the HVDC system is shut off in the power system simulator, and a plurality of voltages can be set by adding the generators bus. In this case, the control unit 130 performs algae calculation by the amount of transmission of the HVDC system and can calculate the reactive power limit value for each voltage according to the HVDC system transmission amount.

Meanwhile, according to one embodiment, the plurality of voltages may be set to 0.95 pu, 1.00 pu, 1.02 pu, and 1.05 pu, respectively.

The AC filter design apparatus 100 calculates the reactive power requirement of the HVDC system (S302).

The controller 130 of the AC filter design apparatus 100 can calculate the reactive power requirement of the HVDC system in response to the converter design technique for the HVDC system.

In this case, the reactive power requirement of the HVDC system may vary corresponding to the converter used in the HVDC system. Specifically, it may vary depending on the type of converter used in the HVDC system, the capacity and design of the converter, and the AC power system associated with the HVDC system.

The AC filter design apparatus 100 calculates the reactive power fluctuation threshold of the AC power system (S303).

The reactive power fluctuation threshold may be a threshold (threshold value) at which the reactive power of the AC power system may fluctuate. The control unit 130 of the AC filter design apparatus 100 can calculate the reactive power fluctuation threshold by summing the reactive power limit value for each voltage according to the transmission amount of the HVDC system and the reactive power required amount for the HVDC system.

The AC filter design apparatus 100 performs capacity estimation and number selection of the AC harmonic filter (S304).

Specifically, the control unit 130 of the AC filter design apparatus 100 can maintain the voltage variation rate at a predetermined value which is a ratio of the voltage holding target value and the voltage holding maximum value. In this case, the difference between the grid reactive power fluctuation threshold value corresponding to the voltage holding maximum value and the grid reactive power fluctuation threshold value corresponding to the voltage holding target value can be calculated as the filter capacity.

For example, the voltage fluctuation rate can be maintained at 2.5%, which is the ratio of 1.05pu to the voltage maintenance target value of 1.02pu. In this case, the filter capacity is 1.05pu and the system reactive power fluctuation threshold corresponds to 1.02pu. It can be calculated as the difference of the reactive power variation threshold.

The controller 130 of the AC filter design apparatus 100 can select the maximum value within the error range within which the voltage can be maintained at the interval between the voltage holding target value and the voltage holding maximum value as the number of filters. For example, the number of filters can be selected as the maximum value within an error range capable of maintaining voltage at 1.02pu and 1.05pu intervals. As a result, the number of filters to be designed can be minimized and economic efficiency can be secured.

On the other hand, assuming that the total amount of reactive power to be compensated by the filter is the same, the smaller the width of the voltage, the smaller the unit capacity of the filter is, and the larger the number of filters is required.

Hereinafter, an example of calculating the capacity and the number of the AC filters for the HVDC system will be described with reference to FIGS. 4 to 7. FIG. In the examples shown in FIGS. 4 to 7, it is assumed that the capacity and the number of the AC filters for the HVDC system according to the AC power system having the voltage of 345 KV are calculated.

FIG. 4 is a graph showing a reactive power limit value for each voltage according to a transmission amount of an HVDC system calculated in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.

The method for calculating the reactive power limit value to enable the reactive power supply within the range allowed by the AC power system is as follows.

First, parameters are set in the HVDC system model from the power transmission point to the power receiving point based on the database of the fifth power supply basic plan using the PSS / E program as the power system simulator. The short circuit level (SCL) of the water receiving point used in FIG. 4 is 3000 MVAr (mega bar), and the rated capacity of the HVDC system is 1500 MW in total.

Thereafter, the HVDC system is shut off at the PSS / E and the generator bus is added to set the voltages to 0.95, 1.00, 1.02, and 1.05, respectively. In this state, by performing the algae calculation for each HVDC capacity, the reactive power limit value for each voltage according to the transmission amount of the HVDC system can be obtained.

In Fig. 4, the X-axis represents the rated capacity (MW) of the HVDC system, and the Y-axis represents the magnitude of the reactive power (MVAr). In this case, the reactive power limit value for each voltage is shown in a graph in FIG.

In particular, the reactive power limits for each voltage between 0.95 pu and 1.05 pu, which is the general allowable range voltage of the domestic AC power system, are shown. Referring to Fig. 4, a graph a shows a reactive power limit value when the voltage is 0.95 pu, a graph b shows a reactive power limit value when the voltage is 1.00 pu, and a graph c shows a case where the voltage is 1.02 pu And graph d shows the reactive power limit value when the voltage is 1.05 pu.

Referring to this, when the voltage increases, the reactive power threshold increases correspondingly. Therefore, the higher the voltage of the HVDC system, the larger the reactive power limit. Also, the reactive power limit generally increases as the rated capacity of the HVDC system, i. E. The HVDC system, increases.

FIG. 5 is a graph illustrating a reactive power requirement of an HVDC system calculated in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.

The reactive power requirement of the HVDC system can be calculated using [Equation 1] as follows.

[식 1]

[Formula 1]

는 역률(Power Factor)이다. 또한,

는 무 부하(no load) DC 전압이고,

는 6 펄스 브리지 DC 전압이다. here,

Is a power factor. Also,

Is a no load DC voltage,

Is a six-pulse bridge DC voltage.

과

는 각각 다음 식에 의해 구해질 수 있다.in this case,

and

Can be obtained by the following equations respectively.

[식 2]

[Formula 2]

[식 3]

[Formula 3]

는 소광각이고,

는 저항 정류를 나타낸다.On the other hand, in Equation 3,

Lt; RTI ID = 0.0 >

Represents resistance rectification.

FIG. 5 is a graph showing the amount of reactive power required in the HVDC system. In this case, the X axis represents the rated capacity (MW) of the HVDC system, and the Y axis represents the magnitude of the reactive power (MVAr).

Referring to FIG. 5, the capacity of the HVDC system is proportional to the reactive power requirement of the HVDC system. Specifically, when the capacity of the HVDC system increases, the reactive power requirement of the HVDC system increases correspondingly. Thus, the larger the capacity of the HVDC system, the greater the reactive power requirement of the HVDC system.

4 and 5, it is possible to secure the stability of the AC power system in the design of the AC filter by calculating the reactive power threshold value and the reactive power required amount, and at the same time, It is possible to select a minimum number of filters capable of supplying power.

FIG. 6 is a graph illustrating a reactive power fluctuation threshold of an AC power system calculated in an AC filter designing process according to an exemplary embodiment of the present invention.

The reactive power fluctuation threshold of the AC power system may be a value obtained by summing the reactive power limit value per voltage according to the transmission amount of the HVDC system and the reactive power required amount of the HVDC system. That is, FIG. 6 is a graph showing the sum of the reactive power limit of the AC power system of the water receiving point and the reactive power requirement of the HVDC system. In this case, the constant voltage at operating the HVDC system is 1.02pu (353kV) or more.

Assuming that the total amount of reactive power to be compensated by the filter is the same, the smaller the fluctuation range of the voltage, the smaller the unit capacity of the filter should be designed. In this case, a larger number of filters are required corresponding to the unit capacity of the filter.

For example, for a 345KV AC power system, the AC filter capacity for the HVDC system is estimated as:

The rate of voltage change shall be maintained at 2.5%, which is the ratio of the maximum voltage holding value to the voltage holding target value of 353 kV (1.02 pu) to 362 kV (1.05 pu). In this case, the step size of the filter can be calculated as a difference between the grid reactive power fluctuation threshold corresponding to the voltage sustain maximum value 1.05pu and the grid reactive power fluctuation threshold corresponding to the voltage sustain target value 1.02pu. Referring to FIG. 7, the grid reactive power fluctuation threshold corresponding to the voltage sustain maximum value 1.05pu is 49 MVAr, and the system reactive power fluctuation threshold value -38 MVAr corresponding to 1.02 pu. Therefore, the step size of the filter is calculated by the difference between the grid reactive power fluctuation threshold of 49MVAr corresponding to 1.05pu and the corresponding grid reactive power fluctuation threshold of -38MVAr corresponding to 1.03pu (49 - (-38) = 90} 90MVAr.

FIG. 7 is a graph illustrating a method of calculating the number of filters in an AC filter designing process according to an exemplary embodiment of the present invention. Referring to FIG.

The number of filters can be selected as the maximum value within the tolerance range in which the voltage can be maintained at the interval between the voltage holding target value and the voltage holding maximum value.

Since it is difficult to maintain the voltage at the maximum output level of the HVDC system, operation of the shunt reactors is essential to maintain the predetermined voltage range when pressurizing the HVDC system. Assuming that there is no shunt reactor, there is a problem that the voltage can not be adjusted downward when the filter is turned on. Therefore, in order to adjust the overall voltage balance, a shunting reactor capable of suppressing the voltage rise due to the filter is required.

In FIG. 7, if only one filter is injected in the interval between 750 MW and 900 MW along the x-axis, the voltage drops to 1 pu. That is, it can not be operated between the graph d (voltage 1.05pu) and the graph c (voltage 1.02pu). Therefore, two filters are put in order to operate the voltage between 1.02pu and 1.05pu in the corresponding section. In the interval between 1200MW and 1350MW, two filters are used for the same reason. In this case, two reactors are necessary in consideration of the voltage downward.

In the initial state of operation, two shunt reactor banks and two filters are put in. The filter is put in 150MW interval from 300MW point, and the shunt reactors are removed at 750MW and 1200MW, so that the voltage is maintained at 1.02pu and 1.05pu intervals In other words, the 90MVAr x 10 bank of filters can be selected as the maximum design unit capacity and the minimum number of design filters.

When designing an AC filter for HVDC system, the filter capacity is calculated considering the reactive power supply limit according to the rated voltage of the AC power system, and the number of filters is selected irrespective of the capacity calculation. In addition, AC filters have been designed empirically according to the characteristics of each HVDC system, without systematic procedures for estimating the capacity of AC filters. Thus, there is a problem that the AC filter design for the system is based on inefficient and unstructured analysis, which increases the time required for the design.

According to the present invention, in designing an AC filter for an HVDC system, the reactive power fluctuation threshold of the system is calculated, and the reactive power fluctuation threshold of the system corresponding to the voltage holding maximum value and the reactive power fluctuation threshold of the system Can be estimated by the filter capacity. Also, the maximum value within an error range in which the voltage can be maintained at the interval between the voltage holding target value and the voltage holding maximum value is selected as the number of filters. Thus, the filter capacity and the number of filters can be calculated systematically and the number of filters can be calculated in association with the filter capacity. With this algorithm, the designer can systematically estimate the capacity and number of AC filters.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various variations and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

100: AC filter designing device 110: inputting part
120: storage unit 130:
210: Reactive power limit value calculation block 220: Reactive power requirement calculation block
230: Reactive power fluctuation limit calculation block
240: Filter capacity calculation and number selection block

Claims (8)

An apparatus for designing an AC filter for an HVDC system,
An input unit for receiving data for calculating a filter capacity and a number of filters of the AC filter; And
Calculating a reactive power fluctuation threshold of the power system to which the HVDC system is connected, setting a voltage holding maximum value and a voltage holding target value of the HVDC system, and setting the reactive power fluctuation threshold value, the voltage holding maximum value, And a controller for calculating the filter capacity and the number of filters based on the filter capacity. The method according to claim 1,
Wherein,
Calculating a first reactive power fluctuation threshold value that is the reactive power fluctuation threshold value corresponding to the voltage holding maximum value and a second reactive power fluctuation threshold value that is the reactive power fluctuation threshold value corresponding to the voltage holding target value, And the difference between the variation limit amount and the second reactive power variation limit amount is calculated as the filter capacity. The method according to claim 1,
Wherein,
And a maximum value within an error range in which a voltage can be maintained at an interval between the voltage holding target value and the voltage holding maximum value is calculated and the maximum value is calculated by the number of filters. The method according to claim 1,
Wherein,
An AC filter design that calculates a reactive power limit value for each voltage according to a transmission amount of the HVDC system and a reactive power required amount for the HVDC system and calculates the reactive power variation threshold by summing the reactive power threshold value and the reactive power required amount Device. 5. The method of claim 4,
Wherein,
And sets the reactive power limit value so that reactive power can be supplied within a range allowed by the power system. The method according to claim 1,
The voltage holding maximum value is 1.05 pu,
And the voltage maintaining target value is 1.02 pu. The method according to claim 1,
Wherein the controller designates the AC filter using a Power System Simulator for Engineering (PSS / E) program. A method of designing an AC filter for a HVDC system,
Receiving data for estimating a filter capacity and a number of filters of the AC filter;
Calculating a reactive power variation threshold of the power system to which the HVDC system is connected;
Setting a voltage holding maximum value and a voltage holding target value of the HVDC system; And
And estimating the filter capacity and the number of filters based on the reactive power fluctuation threshold, the voltage sustain maximum value, and the voltage sustain target value.

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